This invention relates to a hydrotherapy apparatus used in a tub or spa for generating a slowly rotating jet of water to massage a particular area of the body such as the back. In order to achieve this function, the apparatus is incorporated into the wall of a tub or spa and connected to a source of pressurized water. The pressurized water performs two functions. A first portion of the water is directed by the apparatus to form a jet of water. A second portion of the water is used to drive an internal water motor which, through reduction gears, causes the jet of water to be continuously rotated in a circle. This latter function is advantageous in that it assures predictable, smooth rotation of the jet at a slow speed.
Our prior hydrotherapy device is disclosed in U.S. Pat. No. 4,220,145. The hydrotherapy apparatus disclosed in that patent has a nozzle which continuously rotates through a circular path. The rotating nozzle passes through and is rigidly secured to a water wheel with a plurality of paddles. When the apparatus is connected to a supply of pressurized water, a first portion of the supplied water passes through the nozzle in the center of the water wheel and exits the rotating nozzle at its outlet to form an aerated jet. A second portion of water is tapped from the main supply of pressurized water and, by impinging on the paddles, is used to rotate the water wheel and the nozzle. This water is then supplied to the rotating nozzle.
A hydrotherapy apparatus in accordance with the above-described structure, although advantageous in that it generates a rotating jet of aerated water driven by water pressure, does not maximize the therapeutic benefits which can be obtained. More specifically, the hydrotherapy apparatus does not deliver a strong jet of water at a slow rotational speed without significant variations in rotational speed. Because the nozzle is rigidly fixed to the water wheel, any rotational speed variations of the water wheel will be transmitted to the nozzle without reduction. These rotational speed variations are caused by the friction of the water wheel, which includes random sticking points, and also by the speed surge due to each paddle entering the driving jet of water introduced at the water wheel housing. These rotational speed surges contribute to the rotational instability of the water wheel the most at slow speeds.
The most beneficial therapeutic effects of a rotating jet apparatus are enjoyed when a strong jet of water is supplied at slow rotational speed. The strong jet massages the body and releases muscle tension. Any weakening of the jet reduces this therapeutic effect. If the jet is run at a high speed of rotation, the effective force of the jet felt by a particular area of the body is reduced. Rotational speed surges also deprive particular areas of the full force of the jet.
The above-described hydrotherapy apparatus has a valve which regulates the amount of water flow used to drive the water wheel. If most of the water is used to drive the water wheel, rotational speed nonuniformities will be reduced, but the strength of the jet will be weakened, thus compromising therapeutic benefits. If only a small amount of water is used to drive the water wheel, speed nonuniformities will increase. Thus, the benefit of a strong jet must be compromised to obtain the benefit of uniform rotation.